Paula S. Moschella

Interactions between wave action and grazing control the distribution of intertidal macroalgae

Canopy-forming macroalgae are key species on temperate rocky shores. However, there is a lack of understanding of how the relative balance of physical and biological factors controls the establishment and persistence of intertidal macroalgae. Here we present an integrated study of the relative importance of wave-induced forces and grazing for the recruitment and survival of the canopy-forming intertidal macroalgae Fucus vesiculosus and F. spiralis. A set of overtopped breakwaters provided a nearly unconfounded gradient in wave exposure between seaward and landward sides. A biomechanical analysis was performed based on empirical measurements of maximum drag forces in breaking waves, a model of long-term maximum wave height, and the breaking stress of Fucus spp. The estimated maximum flow speed (7-8 m/s) on the seaward side of the breakwaters was predicted to completely dislodge or prune Fucus spp. larger than approximately 10 cm, while dislodgment was highly unlikely on the landward side for all sizes. Experimental transplantation of Fucus spp. supported the biomechanical analysis but also suggested that mechanical abrasion may further limit survival in wave-exposed locations. Experimental removal of the limpet Patella vulgata, which was the principal grazer at this site, resulted in recruitment of Fucus spp. on the seaward side. We present a model of limpet grazing that indicates that limpet densities >5-20 individuals/m2 provide a proximate mechanism preventing establishment of Fucus spp., whereas wave action >2 m/s reduces persistence through dislodgment and battering. In a conceptual model we further propose that recruitment and survival of juvenile Fucus spp. are controlled indirectly by wave exposure through higher limpet densities at exposed locations. This model predicts that climate change, and in particular an increased frequency of storm events in the northeast Atlantic, will restrict fucoids to more sheltered locations.

Historical comparisons reveal multiple drivers of decadal change of an ecosystem engineer at the range edge

Biogenic reefs are important for habitat provision and coastal protection. Long-term datasets on the distribution and abundance of Sabellaria alveolata (L.) are available from Britain. The aim of this study was to combine historical records and contemporary data to (1) describe spatiotemporal variation in winter temperatures, (2) document short-term and long-term changes in the distribution and abundance of S. alveolata and discuss these changes in relation to extreme weather events and recent warming, and (3) assess the potential for artificial coastal defense structures to function as habitat for S. alveolata. A semi-quantitative abundance scale (ACFOR) was used to compare broadscale, long-term and interannual abundance of S. alveolata near its range edge in NW Britain. S. alveolata disappeared from the North Wales and Wirral coastlines where it had been abundant prior to the cold winter of 1962/1963. Population declines were also observed following the recent cold winters of 2009/2010 and 2010/2011. Extensive surveys in 2004 and 2012 revealed that S. alveolata had recolonized locations from which it had previously disappeared. Furthermore, it had increased in abundance at many locations, possibly in response to recent warming. S. alveolata was recorded on the majority of artificial coastal defense structures surveyed, suggesting that the proliferation of artificial coastal defense structures along this stretch of coastline may have enabled S. alveolata to spread across stretches of unsuitable natural habitat. Long-term and broadscale contextual monitoring is essential for monitoring responses of organisms to climate change. Historical data and gray literature can be invaluable sources of information. Our results support the theory that Lusitanian species are responding positively to climate warming but also that short-term extreme weather events can have potentially devastating widespread and lasting effects on organisms. Furthermore, the proliferation of coastal defense structures has implications for phylogeography, population genetics, and connectivity of coastal populations.

Group report: Methodologies to support implementation of the water framework directive

This chapter outlines the basic features and innovative aspects of the Water Framework Directive (WFD). Particular emphasis is given to problems and issues arising from the technical implementation of the environmental objectives set by the Directive. The difficulties of interpretation of key concepts such as ecological status, indicators and reference conditions are discussed in detail, and recommendations are given in order to avoid erroneous evaluation of these terms, leading to serious misclassification of the aquatic ecosystems. The consequences of the implementation of the WFD are also examined within the more specific context of water quality (bathing water quality, pollution by priority substances) and marine protected areas (MPAs). Tools and analyses to achieve environmental objectives and support the integrated management of water resources promoted by the Directive are discussed. It is suggested that models can be a powerful tool for prediction of reference conditions, the ecological classification of ecosystems and operational monitoring. The paper concludes with the importance of using an integrated approach for the implementation of the WFD, which can be achieved only by promoting communications and closer collaborations between scientists, economists and other stakeholders, particularly during the decision making process.

Group report: Global change and the European coast - climate change and economic development

The effects of climate change on economic development in the coastal zone cannot be ignored in future coastal zone management plans. This chapter reports the outcome of the group discussion centred round the three questions posed by Nicholls and Klein on how the coastal zone can be effectively managed in the future. The first question asked how we can marry together the human and natural values of a system in the upcoming decades. The results of the discussion highlighted the utility of using scenarios to obtain good management plans that take into account the three provisions of human safety, economic development and ecological integrity while still achieving a situation of sustainable development. The second question addressed the tools required to achieve these management goals and discusses the role of public participation and media communication. The third question asked what proactive strategies can be used to effectively manage the coastal zone in the 21st Century and an example of the Humber estuary management plan is given. It is proposed that a robust and flexible integrated coastal zone management plan is the only effective way to manage the coastal zone in a sustainable manner in the uncertain face of climate change.